Defrost systems for automobiles typically include a pair of funnel shaped diffuser outlet nozzles which receive heated air from a heating unit to uniformly diffuse and disperse the heated air upon a windshield. This requires two volumetrically large space occupying assemblies as well as two rather long diffuser outlets on the dashbord thereby occupying considerable space both on the dashboard and underneath. With downsized automobiles and impending advent of airbags mounted on the dash, this volumetric space, as well as the exterior space on the dashboard is at a premium. In Kakei et al U.S. Pat. Nos. 3,745,906 and 3,832,939 and in Stouffer U.S. Pat. No. 4,250,799, the defrost air stream is swept across the windshield to achieve better defrost operation and in Stouffer volumetric space underneath the windsheld is reduced through the use of a resilient reed oscillator. However, in these cases, the space occupied on the dashboard for admitting the sweeping airstream is rather lengthy and in the case of the fluidic oscillator disclosed in the Kakei et al patents, as well as the also disclosed auxillary electro-magnetically controlled sweep, these require electrical connections and/or volumetric space which is undesirable.
According to the present invention, the space requirements on the dashboard for sweeping defrost air are reduced by utilizing a fluidic oscillator having an interaction chamber wherein the sidewalls converge to the defrost air outlet and the defrost air is caused to sweep back and forth by a fluidics oscillator having no moving parts. The amount of space on the dashboard normally occupied by the output funnel of the typical defrost system is reduced significantly.
Accordingly, the basic object of the present invention is to reduce the amount of space occupied by the defrost outlet in the dashboard of vehicles such as automobiles, trucks and the like. Another object of the invention is to provide such a defrost system which is inexpensive, requires little underdash space, and which reduces the complexity of underdash defrost systems.